1. Field of the Invention
The invention relates to the field of digital telecommunications and more particularly to an algebraic coder-decoder circuit for Reed Solomon and BCH block codes, usable in telecommunications.
Digital telecommunications suffer from disturbances due, among other things, to the poor quality of the transmission channel or to the intervention of active jammers. Thus, it is necessary to provide an efficient protection for the information.
2. Description of the Prior Art
The conventional methods associate a simple error, parity, etc detection and a procedure for repeating the messages. These messages may be advantageously replaced by the technique of error correcting codes which provide a good compromise between the useful flow rate and the safety of the transmitted data. The problem which limits the use of error correcting codes is related to the complexity of their use. In fact, the implementation of this type of code in general or signal processing microprocessors only allows low rate applications. In fact, coding and decoding uses the processing of value polynomials in the Galois bodies to which these conventional processors are badly adapted.
The French patent application No. 84 08141 in the name of the applicant describes a parametrable coder-decoder circuit usable in telecommunications for processing the data by the above mentioned error correcting codes. The coder-decoder described in this application is preferably a monolithic circuit, an intelligent peripheral of a microprocessor which allows flow rates of several tens of kilobits per second to be reached with high error rates in the transmission channel. This standard circuit is capable of processing all the usual codes of the above mentioned code families in their different versions and without any intervention from the host microprocessor other than the definition of the codes used and the control of the input and output operations. However, the coder-decoder circuit described in the referenced application and generally arranged leads to a high level of complexity without however, allowing polynomials to be processed in the Galois body CG (256) which alone is capable of directly processing the bytes i.e. the information in the form in which it is generally presented.